Chlorine dioxide, which has high oxidizing power, looks promising for applications including deodorization, sterilization, virus removal, mold prevention, antisepsis, and bleaching. However, the chlorine dioxide is extremely unstable and is unsuitable for long-term storage or conveyance. In addition, chlorine dioxide in high concentration involves a risk of explosion. In order to solve these problems, various methods have been proposed.
A gel composition comprising chlorine dioxide and a water-absorbing resin has been developed (for example, see Patent Literature 1), but the composition generates little chlorine dioxide gas. In order to solve the problem, a method of irradiating a gel composition comprising chlorine dioxide and a water-absorbing resin with ultraviolet light has been proposed (for example, see Patent Literature 2), but the method requires a combined ultraviolet irradiation apparatus.
A gel composition comprising a pure chlorine dioxide-generating product containing dissolved chlorine dioxide gas, a chlorite, and a pH adjuster for maintaining the product acidic and a high water-absorbing resin has been developed (for example, see Patent Literature 3), but it is unsuitable for long-term storage due to the degradation of the dissolved chlorine dioxide.
A method of adding an activator, a water-absorbing resin, and a water-retaining agent to an aqueous chlorite solution and converting the mixture into a gel has been developed (for example, see Patent Literature 4). However, the method requires the addition of the agents just before use. In addition, the method fails to control the reaction after the addition of the agents and generates chlorine dioxide gas at high concentration for several days. The method accordingly has problems concerning handling safety issues and concentration control.